Loans - (Loan Portfolio Composition Including Carrying Value by Segment of Loans Accounted for under ASC Topic 310-30) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Loans [Line Items]
Total Loans	$ 3,120,543	$ 2,860,921	$ 2,822,555
% of Total	100.00%	100.00%
Commercial Loan [Member]
Loans [Line Items]
Total Loans	$ 1,807,883	$ 1,560,430
% of Total	57.90%	54.60%
Commercial Real Estate [Member]
Loans [Line Items]
Total Loans	$ 561,654	$ 526,792
% of Total	18.00%	18.40%
Residential Real Estate Segment [Member]
Loans [Line Items]
Total Loans	$ 724,374	$ 744,885
% of Total	23.20%	26.00%
Consumer [Member]
Loans [Line Items]
Total Loans	$ 26,632	$ 28,814
% of Total	0.90%	1.00%
ASC 310-30 [Member]
Loans [Line Items]
Total Loans	$ 125,596	$ 145,852
ASC 310-30 [Member] | Commercial Loan [Member]
Loans [Line Items]
Total Loans	31,875	39,280
ASC 310-30 [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total Loans	79,798	89,150
ASC 310-30 [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total Loans	13,420	16,524
ASC 310-30 [Member] | Consumer [Member]
Loans [Line Items]
Total Loans	503	898
Non ASC 310-30 [Member]
Loans [Line Items]
Total Loans	2,994,947	2,715,069
Non ASC 310-30 [Member] | Commercial Loan [Member]
Loans [Line Items]
Total Loans	1,776,008	1,521,150
Non ASC 310-30 [Member] | Commercial Real Estate [Member]
Loans [Line Items]
Total Loans	481,856	437,642
Non ASC 310-30 [Member] | Residential Real Estate Segment [Member]
Loans [Line Items]
Total Loans	710,954	728,361
Non ASC 310-30 [Member] | Consumer [Member]
Loans [Line Items]
Total Loans	$ 26,129	$ 27,916